1. Technical Field
The present invention relates generally to cellular wireless communication systems; and more particularly to a method for controlling the flow of data communications within such a wireless communication system to provide voice communications capacity as required.
2. Related Art
Cellular wireless communication systems are generally known in the art to facilitate wireless communications within respective service coverage areas. Such wireless communication systems include a "network infrastructure" that facilitates the wireless communications with subscriber units operating within a service coverage area. The network infrastructure typically includes a plurality of base stations dispersed throughout the service coverage area, each of which supports wireless communications within a respective cell (or set of sectors). The base stations couple to base station controllers (BSCs), with each BSC serving a plurality of base stations. Each BSC couples to a mobile switching center (MSC) which also couples to the PSTN, the Internet and/or to other MSCs.
A subscribing wireless unit operating within the service coverage area communicates with one or more of the base stations. The base stations route the communications to the MSC via a serving BSC. The MSC routes the communications to another subscribing wireless unit via a BSC/base station path (which may be the same BSC/base station path when the communications are with another subscribing unit serviced by the same base station) or via the PSTN/Internet/other network to a terminating destination.
Various operating standards have been developed to standardize wireless communications. The wireless communication operating standards include, for example, the Advanced Mobile Phone Service (AMPS) standards, the Global Standards for Mobile Communication (GSM), the Code Division Multiple Access (CDMA) standards and the Time Division Multiple Access (TDMA) standards. These operating standards set forth the technical requirements that facilitate compatible operation between equipment of differing vendors.
These operating standards were initially developed to support voice communications but not data communications. With advances in digital computers and data networking technology, however, it has become advantageous to service data communication as well as voice communications under these operating standards.
Presently, wireless communication systems are required to service data communications with laptop computers, data terminals, and fixed wireless access units, among other data devices, in addition to supporting voice communications. Since creating a completely separate network infrastructure to service only data communications would require a great redundancy in network resources, it has been advantageous to retrofit existing wireless systems that were originally constructed to service only voice communications to also service data communications. In retrofitting wireless communication systems to support both voice communications and data communication, new operating standards must be developed (e.g., IS-99). However, determining how such operating standards should work is difficult, especially considering the differing use patterns for data communications as compared to voice communications.
Voice communications typically last for a few minutes and require a dedicated bandwidth during active periods of a call. At other times, no bandwidth is required and allocated channel bandwidth may be temporarily deallocated. The user controls these bandwidth requirements, not the system operator. Thus, when bandwidth is required for voice communications, it must be provided. Voice communications are typically delay sensitive but can tolerate a relatively high Bit Error Rate (BER).
In contrast, data communications often last for tens of minutes and require significant bandwidth through the duration of the data communications. However, as compared to the voice communications which must be serviced on a real-time basis, the data communications generally don't have such a servicing requirement, but correct replication of data is essential. Thus, the data communications require a relatively low BER as compared to voice communications.
Difficulty in operation of a wireless communication system often results when a substantial amount of available resources are allocated for data communications. When a data communication (or multiple data communications) has/have been initiated, significant bandwidth is typically allocated to the data communication until the data communication is complete. In the case of a CDMA or TDMA system, the data communications may consume multiple code channels or time slots. If a voice communication is initiated during this high bandwidth data communication, it must also be allocated bandwidth by the system. However, if the bandwidth is already allocated to data communications, it is unavailable for voice communications. As a result, the call is blocked. Similarly, ongoing voice communications may be affected by the allocation of such bandwidth for data communications, resulting in bit errors and frame errors.
Thus, there is a need in the art for a methodology that provides sufficient voice communications capacity in such a system so that the voice communications are properly serviced, even during ongoing data communications.